Did slaves continue to play an important role in Norse households? Did the Norse still engage in the slave trade? Did they stop enslaving Christians but continue to enslave non-Christians? If slavery continued after Christianization, how long did it last?
As /u/Platypuskeeper and I discussed in Was Slavery A Part Of The Hanseatic Trade?, slavery (, or, thralldom as a legal concept) in medieval Scandinavia was definitely decline in middle- and long term, and it is difficult to evaluate how directly Christianization of Nordic countries contributed to this trend.
I have to admit, however, to modify one area/ point to my argument above: At least, Northern Crusades since the 13th centuries did not took POW as long-term slaves to be sold somewhere else, but in the 12th century, some chroniclers like Saxo Grammaticus and Helmold of Bosau, and even Snorri Sturluson, note that 'officially' pagan Slavic Wends (Abodrites/ Obodrites) still held a large-scale pagan market in the southern coast of the Baltic, and they sometimes took some Danes and other Scandinavian people away from their homeland to sell there, though it was sometimes difficult to find appropriate buyers for such slaves (Jensen 2017).
It is likely that the Danish conquest (Wendish crusade) against the Wends and successive Christianization in later 12th century probably put an end to this custom among the Wends, but even the conquering Danes still sometimes seemed to maintain some unfree people (i.e. thralls in a legal sense) into their household, as glimpsed from the testament of Archbishop Absalon of Lund (d. 1201) (see the linked post for further details). Thus, the tradition of slavery (thralldom) was not entirely died out at least in the 12th century Denmark, more than ca. 2 centuries after the Christianization, I suppose. So, not so sudden change of the significance of slavery around the turn of the 1st millennium, but rather a gradual transition from the slavery (thralldom) would be a more appropriate model.
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